The present invention relates to a side airbag apparatus, which deploys and inflates an airbag on one side of an occupant seated in a seat of a vehicle to protect the occupant from an impact applied to the vehicle from the side of the seat.
A side airbag apparatus including an airbag and an inflator for protecting an occupant seated in a seat from an impact applied to a vehicle from the side of the seat in the event of a side collision, for instance, is widely known. The airbag of this kind of side airbag apparatus is accommodated in a backrest (seat back) of the seat in a folded state together with the inflator. When an impact is applied to a body-side portion, such as a side door, of the side of the vehicle, the side airbag apparatus supplies inflation gas into the airbag from the inflator. The inflation gas causes the airbag to be deployed and inflated out of the seat with part of the airbag left within the seat back. The airbag is deployed and inflated toward the front of the vehicle into a narrow space between the occupant seated in the seat and the body-side portion. The airbag thus deployed and inflated is positioned between the occupant and part of the body-side portion that protrudes inward into the interior of the vehicle and restrains the occupant, thereby mitigating the impact applied from the side to the occupant through the body-side portion.
The aforementioned type of side airbag apparatus is described in Japanese Laid-Open Patent Publication No. 2011-5908, for example, in which the side airbag apparatus deploys and inflates an airbag in a deployment area encompassing the head and lumbar region of an occupant by means of inflation gas supplied from an inflator in response to impact applied from the side.
As depicted in FIG. 12, an airbag 80 described in Japanese Laid-Open Patent Publication No. 2011-5908 includes a main inflatable portion 81, a head-protecting inflatable portion 82, a lumbar-region-protecting inflatable portion 83, and a non-inflatable portion 84. The main inflatable portion 81 constitutes a rear part of the aforementioned deployment area DA, the head-protecting inflatable portion 82 constitutes an upper front part of the deployment area DA and the lumbar-region-protecting inflatable portion 83 constitutes a lower front part of the deployment area DA. The non-inflatable portion 84 is located between the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83. An upper part of the main inflatable portion 81 and the head-protecting inflatable portion 82 are separated from each other by an upper partition 87 having an upper conducting path 86, while a lower part of the main inflatable portion 81 and the lumbar-region-protecting inflatable portion 83 are separated from each other by a lower partition 89 having a lower conducting path 88. An upper check valve 91 is provided in the upper conducting path 86 for preventing the inflation gas G from flowing from the head-protecting inflatable portion 82 into the main inflatable portion 81, while a lower check valve 92 is provided in the lower conducting path 88 for preventing the inflation gas G from flowing from the lumbar-region-protecting inflatable portion 83 into the main inflatable portion 81.
According to the above-described side airbag apparatus, the inflation gas G is supplied from an inflator 85 into the main inflatable portion 81 when an impact is applied from the side to a vehicle. The upper partition 87 acts as resistance to a flow of the inflation gas G from the main inflatable portion 81 into the head-protecting inflatable portion 82. Also, the lower partition 89 acts as resistance to a flow of the inflation gas G from the main inflatable portion 81 into the lumbar-region-protecting inflatable portion 83. Therefore, the inflation gas G supplied from the inflator 85 cannot easily flow into the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83, so that the inflation gas G is first filled into the main inflatable portion 81. The inflation gas G thus supplied causes the main inflatable portion 81 to be deployed and inflated in an entire rear portion of the deployment area DA.
When the internal pressure of the main inflatable portion 81 increases as a consequence, part of the inflation gas G within the main inflatable portion 81 flows into the head-protecting inflatable portion 82 through the upper conducting path 86, causing the head-protecting inflatable portion 82 to be deployed and inflated in the upper front part of the deployment area DA. Also, part of the inflation gas G within the main inflatable portion 81 flows into the lumbar-region-protecting inflatable portion 83 through the lower conducting path 88, causing the lumbar-region-protecting inflatable portion 83 to be deployed and inflated in the lower front part of the deployment area DA. When the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83 are deployed and inflated in this fashion, the internal pressure of the main inflatable portion 81 is increased. Thus, the main inflatable portion 81 functions as a pillar having high strength and thereby restrict the head-protecting inflatable portion 82 from swinging downward and the lumbar-region-protecting inflatable portion 83 from swinging upward. This serves to improve stability of the shape of the airbag 80 which has been deployed and inflated. Accordingly, when the vehicle's body-side portion intrudes into the vehicle interior as a result of an impact that activates the side airbag apparatus, the head-protecting inflatable portion 82 is positioned on the side of the head PH of the occupant P and the lumbar-region-protecting inflatable portion 83 is positioned on the side of the lumbar region PP.
Further, the upper check valve 91 and the lower check valve 92 prevent the inflation gas G from flowing from the head-protecting inflatable portion 82 into the main inflatable portion 81 and from the lumbar-region-protecting inflatable portion 83 into the main inflatable portion 81, respectively. It is therefore possible to increase the internal pressure of the main inflatable portion 81 at an early stage of deployment and inflation of the airbag 80 and then deploy and inflate the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83 without causing these portions 82, 83 to swing downward or upward. After the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83 have been deployed and inflated, the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83 maintain a high internal pressure so that these portions 82, 83 can protect the head PH and the lumbar region PP, respectively.
In the meantime, the side airbag apparatus is configured so that the airbag 80 is deployed and inflated in the space between an occupant P seated in the seat and the vehicle's body-side portion to absorb an impact as described above. Thus, the space allowed for deployment and inflation of the airbag 80 is narrower as compared to other types of collisions than a side collision (e.g., a frontal collision). This space for deployment and inflation of the airbag 80 varies with the size of the vehicle. Generally speaking, the smaller the vehicle size, the narrower the space. Furthermore, the space available for deployment and inflation of the airbag 80 varies with the body size of the occupant P; that is to say, the larger the occupant P, the narrower the space. What is important is that the airbag 80 can be reliably deployed and inflated in such a narrow space to reliably protect the occupant P.
Under such circumstances, it has been proposed to maintain a space for deploying and inflating the head-protecting inflatable portion 82 and the lumbar-region-protecting inflatable portion 83 by pushing and moving the occupant P more inward into the vehicle interior by the main inflatable portion 81, which is deployed and inflated.
The side airbag apparatus described in Japanese Laid Open Patent Publication No. 2011-5908 is configured such that the main inflatable portion 81, which is deployed and inflated, pushes the occupant P into the vehicle interior in the back PB. However, as viewed from above, since the outline of the back PB of the occupant P curved inward of the vehicle toward rear end of the vehicle, it is difficult to push the back PB inward by the main inflatable portion 81 and move the occupant P farther inward into the vehicle interior. Accordingly, it is desired to efficiently move the occupant P more inward into the vehicle interior by maintaining an airbag deployment space to provide improved performance for protecting the occupant P.